A conventional brushless direct current motor (hereinafter referred to as fan motor) comprises a stator and a rotor being rotatable with respect to the stator. The stator has windings to establish alternating magnetic field when an electric current having opposite directions alternatingly flows through the windings. The rotor has a permanent magnet to establish a permanent magnetic field. The magnetic field of the stator interacts with the magnetic field of the rotor to drive the rotor to rotate.
During operation, the electric current flowing through the windings is required to be regularly shifted in directions. Conventionally, such a shift is accomplished by use of an IC (Integrated Circuit) such as a Hall element that can sense position of the rotor. Once the IC senses a predetermined position of the rotor, the IC sends a signal to a control circuit to change the flow direction of the electric current.
FIG. 7 shows a conventional motor. The motor comprises a printed circuit board 30, a stator coils assembly (not labeled), a rotor (not shown) pivotably surrounding the stator coils assembly, an IC 10 and an insulating frame 40 mounted on the printed circuit board 30. A plurality of holes (not labeled) is defined in the printed circuit board 30. A plurality of pins 101 extends from the bottom end of the IC 10 into the holes of the printed circuit board 30 respectively. Since the IC 10 is supported on the printed circuit board 30 only by the pins 101, it is possible for the IC 10 to become slanted during transportation thereof or when the fan motor is subject to vibrations or shocks. If the slant of the IC occurs, the IC 10 can no longer properly sense the position of the rotor. As a result, the directions of the electric current flowing through the windings can not be regularly shifted, thereby causing malfunction of the fan motor.